Accelerating device



Jun 4, 19 9- E M. CLAYTOR ET AL ACCELERATING DEVICE Filed June 25 1927 INVENTORS Charles HHodgkins clnd Edwqrgq M Clayton AT'TORNEY .Batented June 4, 1929.

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AND CHARLES H. HODGKINS, OF PITTS- WESTINGHOUSE'ELECTBIG & MANUFAO- accnnmrme nnvrca.

Application filed June as,

I Our invention relates to motor control ilevices and particularly to devices for controlling the acceleration of motors or other electric energy translating devices.

An object of our invention is to provide a control device forcont-rolling the acceleration of motors, or the initiation/of electroresponsive devices, -in accordance with a predetermined sequence oftime interval, that shall be simple in construction and easily manufactured.- e

other object of our invention is to provide means for accelerating or initiating devices, whereby the sequence or speed. of initiation or acceleration may be adjusted. ,to any desired value. I

.A further object of our invention is to provide an accelerating or initiating device that dependsfor its operation upon the change in magnetic permeability, affected by heat, of thel element which effects the rateor speed of acceleration or initiation. A still further object of our invention is to provide a switching device having a thermally controlled time elementofoperation. i

In practicing our-invention we provide anelectro-magnetically operable switch and means for so controlling the operation there'- of that the initiation or acceleration of devices controlledby the actuation of the switchfrom one position to another may be adjusted or regulated as desired.

For a fuller understanding'of our invention reference may be had to the following description taken in conjunction with the accompanying drawings wherein,

Figure 1 is a view, in side elevation, of an electro-magnetic accelerating or initiating device-embodying our invention.

Fig. 2 is a fragmentary view, partially in section, taken on line II-II of Fig. 1;

Fig. 3 is a view illustrating a modification of secondary coil shown in Figs. 1 and 2; and v Fig. 4 is a-schematic illustration of circuits and apparatus embodying our invention.

Referring to the drawing, we have there illustrated our invention as applied to an alternating-current 'el'ectro-ma'gnetic switch or circuit interrupter 10 that comprises a stationary core 11 of substantially U-shape,

n rmature 12, and an actuating coil 13 a circuit interrupting 1927. Serial, No." 201,524.

that is supported by theuppe'rleg of the core 11. It is to be understood "that the switch 10 may be provided with single, double or a plurality of poles, as desired, de-' pending upon the particular which the switch may be appli application to The armature 12 may be pivotally sup-- ported on a hinge pin a movable switch arm pivotall sup orted by a hinge pin 16 that passes t roug a lug portion 17 of the core. The upper end of the arm 15 is provided with a contact tip 18 that, has engagement with a stationary contact tip 19 when positioned as shown in Fig. 1 .ofthe drawlngs To a rearwardly extending portion or tail piece 21 of the arm 15, a permanent magnet 22 and a contact bridgin member 23 are secured for a purpose to be hereinafter set 14 thatis carried by 15 which in turn is forth. The bridging member'is carried by a clip 24 that may be insulatedfrom the tail piece by a strip 25 of suitable insulating material. L It is to be understood that the permanent magnet 22 maybe either in the form of a bar magnet or one of substantially U-shape, as desired.

The contact bridging member 23 cooperates with a pair of resilient spaced contacts 26 (onlygone of which is shown) that are located irectly abovethe tail piece and in such position that they are engaged by the bridging member when the switch 10 is in position the coil 13 is deenergized.

The entire switch mechanism may be supthat is, when ported on a base or panel 27 of insulating material in accordance practice.

The resilient conta ingly mounted on st of which is shown) and springs 31, the on the base 27. I

In order that the switch 10 in, or restrained to, cuit interru mined length with the customary lldbOltS 28 (only one bymeans of screws 29 stud bolts being mounted may be held its open circuit or cirting positionfor a predeter of time after the coil 13 has been-ener ized, an electromagnetic time delay thermal evice 33 is provided. The thermal device. comprises a bracket or yoke 34 (of magnetic material of substantially U-shape, a primary induction coil 3 5, asecondary coil cts 26 maybe yield- 36, and a core 37, the core being common to both coils and extending through an opening '38 in the yoke to complete a magnetic circuit comprising the yoke and the core.

lhe core has screw thread engagement with the yoke in order that the reluctance of the magnetic circuit may be so varied that the amount of current induced in the secondary coil may be adjusted to any predetermined value. The yoke, core and the induction coil may be considered as a-transformer structure, which structure may be mounted 'on the panel 27 as shown. V

The secondary coil may comprise one or more turns. When one turn is utilized, the coil may be made by a simple stamping oper ation from a blank of relatively thin mate- .rial as shown in Figs. 1 and 2. The lower portion of the coil 36 is provided with an opening 39 through which the core 37 extends and the upper portion of the coil is provided with an opening 41, the openings eing connected by a, slot 42 (see-Fig. 2)

The upper end of the coil 36 is bent over at an angle in order that the permanent magnet 22 will be in contact therewith when the switch is in the open circuit position,-

The material of which the "coil 36 may be made is of suchv character'that' when normally cool it is-magnetic, but when heated to a temperature of a predetermined value the material becomes non-magnetic. Thus it is evident that so'long as the material, of which the coil 36 is made, is cool and magnetic the magnet will be held in engagement therewith because of the magnetic attraction therebetween, but if the coil 36 is heated to a temperatureof apredetermined value, at

., which temperatureit becomes non-magnetic,

the magnet will-not be held in .engagement therewith by magnetic attraction.

The attraction between the permanent magnet 22 and, the coil 36 when magnetic is of such value as to cause the switch 10 to remain in a'circuit'breaking position, even though the coil 13 has been energized but,- if the coil 36 is heated to the temperature at which it becomes non-magnetic the magnetic pull of the coil 13 will cause the switch 10 to be actuated to its circuit closing position as shown in Fig. 1- of the drawings.

The coil 36 may be an alloy of approximately 35% nickel and 65% iron with minor additions of impurities. Such an alloy has the characteristic that when normally cool .it is magnetic but when heated to a temperature of approximately 150-.C. the material becomes non-magnetic. If the material is permitted to cool again below the temperature, thematerial or alloy again becomes .magnetic. Because of this magnetic characteristic-the allo may .be deslgnateda reversible magnet1c alloy, and the coil 36 a reversibly magnetic member.

It is tobe understood that other alleys may be used but the one herein described has been found to be quite satisfactory for our present purpose.

The length of time required to heat the coil 36 by induction to a temperature of substantially 150 maybe regulated or adjusted by theadjustable core 37, that is, the

length of air gap between the right hand lower portion. This is desirable because only the upper portion of the coil that. engages the magnet 22 need be heated to the temperature at which it will become nonmagnetic.

If the secondary coil '36 comprises .more than one ,turn, it may .be constructed as shown in Fig. 3. As there illustrated, the coil comprises a plurality of turns the terminals of which are electrically connected by a member 36a: of reversibly magnetic material. In this modification, the member 36a will be heated more intensively than the may be substantially similar to 'the upper portion of the coil 36 as shown in Figs. 1 and 2.

In Fig. 4 of the drawings one application of the device shown in Fig. 1 is illustrated in which the acceleration of a three phase alternating current motor 47 is controlled. The motor 47 may be connected to supply conductors 48, 49 and 51 by means of a three pole circuit interrupter 52. Betweenv the circuit interrupter .52 and the motor 47 resisters 53 are connected in series with motor. The reslstors may be short-circuited, after the circuit interrupter 52 has been closed for a predetermined length of time, by a three pole switch 54 that is similar in operation and construction to the switch 10 illustrated in Fig. 1. 7 I The circuit interrupter 52 is provided with a closing coil 55 that is connected in parallel with the coil13of Fig. 1. The motor may be energized by closing a starting switch 57, upon theclosing of which a circuit is established from the conductor 49 through the starting switch 57, a stopping switch 58, the coil 55, and a conductor 59 tothe supplyconductor 51. 'Since'the coil 13is connected in parallel with coil 55, the coils are energized simultaneously.

In order that the starting switch 57 may be released to the position shown in Fig. 4 andso that the coils 55 and 13 may be main tained in an energized condition, an interlock 61 is provided. The interlock maybe vactuated mechanically into engagement with stationary t e main circuit interrupter 52' is ina cirvcuit closing position,

the switch 10, designated by the three pole circuit interrupter .54 in Fig.3, is revented from closing upon the closing of t e switch 52 because of the magnetic attraction between the magnet and the coil 36, until the coil 36 has been heated to its non-magnetic state. Thus, it is' seen that the resistors 53 are caused to be in circuit with the motor 47 to thereby limit the initial current through the motor to a safe value until it has accelerated to a predetermined speed.

When the motor has increased in speed to such a value that the current through the motor has dropped to a reasonably small 'value, the coil that temperature at which it becomes nonthe contact bridging by contacts 67.

36 will have been heated to magnetic.- When this temperature is attained the three pole circuit interrupter 54 is actuated to a circuit closing position, thereby shunting the motor circuit and causing full voltage to be applied to the motor 47, which is the desired operating voltage of the motor.

The coil 36 is designated schematically in Fig. 3 by a coil 64, the coil 35 by a coil 65, member 53. y a, bridg ing member 66 and the resilient contacts 26 Whenvthe" starting switch 57 has been closed to complete the energizing circuit of ergizing circuit being the coils 13, and 15, and the interlock 61 has een actuated to a circuit closing position, the coil 65 will have been energized, .the enfrom the supply con ductor 49 through the interlock 61, conduc tor 68, contact bridging member 66, the coil 65-and a conductor-69, to the conductor 51. When the coil 65 is energized, the coil 64 will have a current induced therein, which will cause the same to be heated to the temperature at which itbecomes non .-magnetic at which temperaturethe "coil 13 will be effective to cause the her 66 (contact bridging member 23 in Fig. 1) to'be actuated to its circuit interrupting 65. been deenergized by the deenergization of the coil 65,'wil1 be permitted to cool to the tem erature at which it becomes magnetic so that the accelerating or initiating switch 10 may again be ready for operation.

Various modifications may be made in the device embodying our invention without departing from the spirit and the scope thereof. We desire therefore that only such limitations shall be placed thereon as are imresistors 53 out. of the .and a core, said core position,

contact bridging memposed by the prior art and the appended claims.

We claim as our invention:

1. In combination, a switch, an electro member has been heated to a temperature of a predetermined value, means energized substantially simultaneously with the energization of said {coil for heating said magnetic member by electromagnetic induction, and means for varying the rate of heating of said member. 7

2. In combination, a switch, an electromagnet coil for actuating said switch from one position to another, a permanent magnet carried by said switch, a reversibly magnetic member for maintaining said switch in one position, when normally. cool, against the magnetic pull of said electromagnet coil and for releasing said switch when said magnetic member has been heated to 'a temperature of a predetermined value, and means for heating the magnetic member by transformer action, said means: comprising a primary coil being common to said primary coil and magnetic member.

3. In combination, a switch, an electromagnet coil for actuating said switch from one position to another, a permanent magnet carried by said switch, a reversibly magnetic member for maintaining said switch in one when normally cool, against. the magnetic pull of said electromagnet coil and for releaslng said switch when said magnetic member has been heated to a temperature of a predetermined value, and means for heating the magnetic member by transformer action, said means comprising a primary coil, a core, said core being common to said primary coil and magnetic member, and means for varying the reluctance of said core, whereby the rate of heating of said reversibly magnetic member may be adjusted to any predetermined value.

4. In combination, a switch, an electromagnet coil for actuating said switch from electromagnet coil and for releaslng and switch when said magnetic heating said magnetic lit) I actuation of said switch from its restrained position to another position, whereby cooling of said reversibly magnetic -member to a temperature at which it becomes magnetic is eifected. i

5. An electromagnetic thermal time-delay device for delaying theactuation of a cir- Hcuit interrupter from .one position to another, said devicecomprising an induction coil and a short circuited coil of reversibly magnetic material inductively coupled thereto, said. reversibly magnetic member being magnetic when normally cool and'nonmagnetic when heated to a-temperature of a predetermined value.

6. An electromagnetic thermal time-delay device for delaying the actuation of a circuit interrupter from one position to another, said device comprising an induction coil, a short eircuited coil of reversibly magnetic material inductively coupled thereto, said reversibly magnetic material being magnetic :when normally .cool and non-mag,

net'ic when heated to a temperature of a predetermined value, and means for varying the reluctance of said magneticvcircuit whereby the rate of heating said magnetic reversible material may be'adjusted to a predetermined value.

7 The co bination with a circuit interrupter, and a magnet coil for actuating said circuit interrupter from one circuitcontrolling position to another, of electromagnetic time-delay thermal means for delaying the actuation of said circuit interrupter from one position to another for a predetermined .length of time after the energization of said magnet coil,'said; means comprising a permanent magnet carried by said interrupter, a reversibly magnetic member engaging said magnet for restraining the interrupter from movement when'normally coolbut for releasing the same when heated to a temperature of a predetermined value, and an in-' duction coil inductively coupled to said reversibly' magnetic member for'causing the same to be'heated to said temperature.

8. In combination, a switch, a closing coil therefor, and means for delaying the closing of said switch fora predetermined length of time after the energization of said closingcoil, said meanscomprising a reversibly magnetic member, a permanent magnet for holding said switch in one position by the magnetic attraction between said reversibly magnetic member and the permanent magmagnetic when normally cool and non-magnetic when heated to a temperature of a predetermined value, and an induction 0011 for net, said reversibly magnetic member being i I inducing an electric current in said reversiition by the magnetic attraction between said reversibly magnetic member and the permanent magnet, said reversibly magnetic member being magnetic when normally cool and non-magnetic when heating to a temperature of a predetermined value, an induction coil for inducing an electric current.

in said reversibly magnetic member by induction whereby said reversibly magnetic member is heated to a temperature at which it becomes non-magnetic and means for varying the amount of current induced .in

said reversibly magnetic member.

10. In combination, a switch, a closing coil therefor, and means for delaying theclosing of said switch for a pre etermined length of time after the energizati n of said closing coil, said means comprising a reversibly magnetic member, a permanent magnet for holding said switch in one position by the magnetic attraction between said reversibly magnetic member and the perpermanent magnet, said reversibly magnetic member. being magnetic when normally cool 7 and non-magnetic when heated to a temperature ofa predominated value, an induction coil for inducing an electric current in said reversibly magnetic member by induction whereby said reversiblymagnetic member is heated to a temperature at which it becomes non-magnetic, and means for deenergizing' said induction coil subsequently to the heat;

.ing of said reversibly magnetic member to the temperature at which it becomes nonmagnetic. I

In testimony whereof, we have hereunto subgcribed our names this 21st day of J unc, 192 I P1 EDWARD M. CLAYTOR.

CHARLES H. HODGKINS. I 

